Medical Cannabis Potency Testing Project

Given the rapidly growing use of medical cannabis for a wide variety
of indications and
the manifold different underground sources currently supplying patients, there is a
natural interest
in investigating the potency, purity, and chemical content of the available supplies of
medical cannabis. While the availability of medical cannabis has increased in the wake of
the passage
of California's Proposition 215 and other state medical marijuana initiatives, scientific
research on
its content remains frustrated by the continued federal ban on medical cannabis research.

In an effort to cast light in this obscure area, a research project was
undertaken by a group
of us, including researchers, growers, and medical cannabis buyers' clubs, with support
from California NORML and MAPS, to analyze samples of medical cannabis from various
patients' cooperatives and providers around the country. This effort proved to be a lesson
in the
difficulties and uncertainties of cannabis research in a society where freedom of
pharmacological
research has been stifled by an effectively totalitarian drug bureaucracy.

From the outset, our project was frustrated by a lack of access to
qualified research labs with expertise in analysis
of cannabis. The leading research lab in the country declined to do business with us
for fear of compromising government contracts, while the other likely
candidates were all foreign and thus not legally accessible to us because of DEA
regulations. In the end, we were fortunate to obtain
the services of a laboratory that had the requisite DEA license and equipment (a
gas chromatograph mass spectrometer, or GCMS), but no prior experience in
cannabis analysisin fact, its primary business was drug urinalysis! The analysis of
our samples was accordingly a learning process for both the lab and ourselves.

Our original aim had been to obtain a broad-spectrum quantitative analysis of
as many of the 60-plus naturally
occurring cannabinoids as possible, in the hope of detecting differences that might
produce differing therapeutic effects among the samples. To our disappointment,
however, our lab could obtain laboratory standards only for the three most common
cannabinoids, delta-9-THC, cannabidiol (CBD), and cannabinol (CBN).

A total of 47 different samples of medical cannabis were submitted by over
a half dozen different providers and patients' cooperatives ranging from California to
the East Coast. Included were 42 samples of sinsemilla bud, three samples of hashish
or resin; one liquid sample of a milk-based cannabis drink ("Mother's Milk"),
and
one capsule of an oral whole leaf preparation.

Upon analysis by GCMS, the potency of the 42 sinsemilla samples was
determined to range from 10.2% to 31.6% THC, with a mean of 19.4%. These results
were surprisingly high, given that the average potency of marijuana in the U.S. has
been typically estimated at around 3% to 4% by NIDA, with higher grade
sinsemilla ranging towards 10% - 15%. The highest potency recorded came from a sample
of hashish, which registered 68.6%. Yet even a sample of Mexican commercial
grade registered a surprisingly high 11%, twice what we had expected. All of this cast
a troubling shadow of doubt on our test results, although it appeared likely that
we were dealing with highly potent varieties.

In contrast, the CBD levels observed were surprisingly low. Only four of
the sinsemilla samples had more than 0.3% CBD, and 35 of them had only
trace amounts (<0.1%). However, one sample had an astoundingly high CBD content
of 28.0% (plus 11.6% THC). Another registered 5.6% CBD and 13.4% THC.
Aside from these two anomalies, the CBD results were frankly disappointing, as we
had hoped to discover significant variations in the content of the samples, with
accompanying variations in medical activity. Because CBD is suspected to have
peculiar efficacy for control of muscle spasms and for damping anxiety and "panic
reactions" caused by THC, we had hypothesized
that certain patients would tend to prefer high-CBD varieties. In fact, however, it
appears that few patients are ever exposed to high-CBD cannabis. Unfortunately, we
were unable to procure additional specimens of the high-CBD varieties for further testing.

As for CBN, the majority of samples
showed only trace amounts. The
highest level detected was 1.4%, and only one
other sample tested above 1%. CBN is a breakdown product of THC, so high CBN
levels are expected in old, degraded samples. This was confirmed by the fact that one of
the samples above 1% CBN was known to be a year old. The prevalence of low CBN in
the samples was evidence that most available medical cannabis tends to be fresh
and well-preserved. Otherwise, these results were of limited interest, as there are few
if any known medical effects of CBN.

Another disappointing surprise was the failure to detect more than trace
levels of THC or CBD in the liquid "Mother's Milk" sample. Upon further
investigation, the lab determined that this was because
it is impossible to extract cannabinoids from fat-based liquids using standard
methanol extraction techniques. Consulting with other researchers, we found that there is
no known method for isolating THC from fat-based liquids.

Later, we located a lab that claimed to have developed a secret,
proprietary method for extracting cannabinoids
from fat. With considerable difficulty, we arranged to have the lab test the
Mother's Milk. To our disappointment, however, once again only trace amounts of THC
and CBD were detected. Just to make sure, one of us swallowed a sample of the
Mother's Milk (which by now had spent several months in the freezer) and found it to
be delightfully potent. Evidently, the lab's technique had failed. It appears that
further advances in testing technology will be needed in order to properly analyze
fat-based oral cannabis products such as Mother's milk, bhang, ghee, and
possibly baked goods such as brownies.

Table: THC and CBD Test Results

(Round 1 vs. Rounds 2 and 3)

1st Round

2nd
Round

3rd Round
(New Lab)

Name of Sample

THC
-1

CBD-1

THC-2

CBD-2

THC-3

CBD-3

High CBD

11.6%

28.0%

4.0%

16.2%

2.8%

8.8%

Sinsemilla BB 006

25.2

<.1

18.2

<.1

14.9

<.1

Sinsemilla BB 008

27.4

<.1

35.1

<.1

21.0

0.07

Sinsemilla MR001

18.0

<.1

11.7

<.1

Sinsemilla BB 009

10.2

1.3

7.6

2.8

Sinsemilla SCJ

14.2

<.1

14.1

<.1

Sinsemilla BB 007

21.1

<.1

12.8

<.1

Sinsemilla Tri 501

27.2

<.1

20.0

<.1

Sinsemilla BB 010

18.0

0.3

8.7

<.1

Sinsemilla BB 004

18.6

<.1

13.0

<.1

Sinsemilla AQ

23.7

<.1

17.6

<.1

Hashish

68.6

0.1

44.0

<.1

Mother's Milk

<.1

<.1

<.1

NIDA Leaf

3.9%

<.1

Low-grade Leaf

2.1

<.1

The extraordinarily high THC potency in the
sinsemilla samples raised troubling doubts about
the reliability of the test results. The lab director
expressed concern about the sample preparation, saying that he
had noted a tendency for the oils to separate from the rest of the
liquid during extraction. We therefore decided to re-submit some of the
samples for a second round of testing. We selected six samples, including the one with
anomalously high CBD. As a check, we added two new samples with presumably low
potency: a sample of low-grade leaf, and some of
the government's own marijuana, grown for NIDA, whose potency is known to be in
the 2.9 - 3.9 % range.

In the second round of testing, the average THC potency for the seven
samples declined slightly to 15.1% from 17.8% in the first round. For the six
low-CBD samples, second-round potencies varied between 65% and 128% of their
first-round values (see table). The high CBD
sample registered a precipitous decline of 60 - 65% in both THC and CBD, bolstering
suspicions of some kind of irregularity in
the sample. NIDA's marijuana came in at 3.9%, at the high end of its expected range,
and the low-grade shake came in at 2%. One sinsemilla sample registered a record
35% on re-testing.

The second round of testing failed to dispel our uncertainty about the
results. Overall, the trend of the data seemed to confirm our suspicions that the first
round results had been systematically too high. However, the wide variation in
individual test results between the two rounds undermined confidence in any
firm conclusions. While it seemed reasonable to infer that we were dealing with
some genuinely potent cannabis, the
high-range results for NIDA's pot suggested that
the second round might still be too high.

After some months of head-scratching, we stumbled upon the opportunity to
re-check our test results via a circuitous route to a second lab. This lab, recognized for
its expertise in cannabis potency testing, was the same one that tested
the Mother's Milk. In addition to the Mother's Milk, we
submitted seven sinsemilla samples, the high-CBD sample, and
the high-potency hashish. The potencies were uniformly lower
in the third round than the first, by proportions ranging from
25 - 50%. All of this clearly implied that our first round test results had been
systematically on the high side. Still, the
average potency of the seven sinsemilla samples was an impressive 15.4%, four or five
times greater than NIDA's marijuana.

From this, we can safely conclude that the marijuana currently being provided
by underground cannabis clubs is far superior in quality to that currently provided
by NIDA to the eight legal medical marijuana patients. Due to its higher THC
content, patients need consume only a fraction of the harmful, non-medically-active tars
and gases in cannabis smoke in order to achieve the same effective dose. This is of
course especially significant in light of the
recent Institute of Medicine report, which singled out smoking as the major adverse
health hazard of medical marijuana. Aside from THC, we could find no significant
presence of the other tested cannabinoids, CBN and CBD, except in one or two
anomalous samples. There is thus little evidence
that patients are currently making use of differing varieties of cannabis to
treat different medical conditions, although it is possible that other, untested
cannabinoids remain lurking in the background.
Finally, our experience shows that laboratory measurements of cannabinoid content
can vary widely from test to test and lab to lab, and are entirely undependable in the
case of fat-based cannabis liquids.

LAST PARAGRAPH REVISED 12/2/02

Later, we located a lab that claimed to have developed a proprietary
method for extracting cannabinoids from fat. With considerable
difficulty, we arranged to have the lab test the Mother's Milk. At
first, we were disappointed when it reported what seemed to be
negligible traces of THC, only 50 parts per million (0.0050%) by
weight. On further consideration, however, we realized that this was
a reasonable concentration for a comestible product, since the weight
of a one cup serving of milk (about 250 grams) was much greater than
that of one cigarette (<1 gram). This works out to 12.5 milligrams of
THC per cup, equivalent to two and a half standard 5 mg Marinol
capsules.